Bag closure



1958 A. F. OTTINGQER ETAL 2,855,881

BAG CLOSURE Filed Jan. 20. 1956 FIG. 2

United States Patent BAG CLOSURE August F. Ottinger, St. Louis, and Bradford R. Stetson,

Kirkwood, Mo., assignors t0 Bemis Bro. Bag Company, St. Louis, Mo., a corporation of Missouri Application January 20, 1956, Serial No. 560,447

2 Claims. (Cl. 112-262) This invention relates to bags, and more particularly to stitched closures for paper bags.

Among the several objects of the invention may be noted the provision of an economical stitched closure for paper bags such as are used for fertilizer or other materials which release acid when subjected to moisture, which is adapted to plug the needle holes made in the walls of the bag as a result of the stitching operation, and which is adapted to retain its strength even though subjected to acid conditions; the provision of a closure of this class which may be stitched without difiiculty as to thread tension and without requiring the use of any coolant for the needle of the sewing machine except under extreme conditions; and the provision of a closure of this class which remains efliective to plug the needle holes even under strain. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

Fig. 1 is a perspective view of the mouth end of a paper bag provided with a stitched closure in accordance with this invention, parts being broken away;

Fig. 2 is an enlarged section taken on line 22 of Fig. 1;

Fig. 3 is an enlarged section taken on line 3-3 of Fig. 2; and

Fig. 4 is a View of a fragment of a stitching thread used in forming the closure of this invention.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to the drawings, there is indicated at 1 in Fig. 1 a paper bag having a closure generally designated 3 comprising a line of stitching securing together the walls of the bag adjacent one end of the bag. The bag 1, for example, is of a type such as is customarily used for fertilizer or other materials which may release acid it moistened. Usually it is a multiwall paper bag. It may have gussets as indicated at 5, or may be a fiat bag. The closure may also include a conventional paper tape 7 folded around the mouth of the bag, and a conventional filler cord 9.

As herein illustrated, the stitching comprises a needle thread 11 having loops 13 extending from one side of the bag through the filler cord and tape and through needle holes 15 in the bag Walls, and a looper thread 17 on the other side of the bag securing the loops from pulling out through the needle holes. It will be understood that the needle holes are made in the bag as a result of driving the needle through the bag walls to carry the loops 13 through the walls. The stitching may be of the conventional chain stitch or lock stitch type. It may also be single-thread type of stitching, instead of a two-thread type.

Patented Oct. 14, 1958 In accordance with this invention, both the needle thread 11 and the looper thread 17 consist of at least one core strand 19 of a synthetic plastic material, preferably nylon, resistant to acid which may be released by the bag contents if moistened, and a plurality of strands 21 of cellulose fiber material, such as cotton or rayon, for imparting bulk to the thread. As herein illustrated, each thread has one core strand 19 and five bulking strands 21. Each may consist, for example, of five strands of No. 12 cotton and one strand of 630 denier nylon. The nylon may either be pretwisted or not. The combination nylon-cotton thread is twisted, with 4.75 twists per inch, for example. The looper thread may be a lighter weight thread than the needle thread.

The total diameter of the needle thread 11 is such that the two portions of the loops 13 in the needle holes 15 are sufficiently bulky tosubstantially plug the needle holes, as shown in Fig. 3. looper thread 17 is such that it is sufiiciently bulky to overlie the needle holes. Plugging of the needle holes by the needle thread prevents the contents of the bag from sifting out through the needle holes.

The core strand 19, being acid-resistant, retains sufficient strength even though attacked by acid to minimize the danger of breakage of the closure, even though the cotton or rayon bulking strands 21 (which are not acidresistant) quickly lose a major portion of their strength when attacked by acid, and contribute very little to the closure strength. However, the cotton or rayon strands retain their bulk to remain effective for plugging the needle holes. The core strand, being more elastic and stronger than the cotton or rayon bulking strands, whether or not subjected to acid attack keeps the cross section of the needle thread effective for plugging the needle holes under strain to which the stitching may be subjected due to rough handling of the bag.

The combination nylon-cotton or nylon-rayon threads, unlike all-synthetic threads, handle in the sewing machine like plain cotton thread, and are easy and economical to use. For example/they do not require unconventional changes in thread tensioning, and do not require the use of coolant for the needle of the sewing machine unless operated at high speed for long periods of time. The nylon core strand is mildew-proof. It is contemplated that acid-resistant synthetic plastic materials other than nylon may be used for the core strand, such as polyacrylonitn'le fiber sold under the trademark Orlon and a synthetic fiber made by the condensation of dimethyl terephthalate and ethylene glycol sold under the trademark Dacron.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. A closure for a bag such as is used for fertilizer or other materials which may release acid if moistened, comprising a line of stitching securing together the walls of 1 the bag adjacent one end, said stitching comprising a thread having portions extending through needle holes in the bag walls, said thread being a composite thread comprising at least one core strand of acid-resistant synthetic plastic material selected from the group consisting of nylon, polyacrylonitrile fiber, and a synthetic fiber made by the condensation of dimethyl terephthalate and ethylene glycol, and a plurality of bulking strands of cellulose fiber material selected from the group consisting of cotton The total diameter of the and rayon, said composite thread having a total diameter such that the portions thereof which extend through the needle holes substantially fill and plug the holes to prevent the contents of the bagirorn sifting out through the needle holes, said core strand retaining sufficient strength to minimize danger of breakage of the closure even though attacked by acid and acting to maintain the cross section of said portions of the thread which extend through the needle holes elfective for plugging the holes.

2. A closure as set forth in claim 1 wherein said composite thread is the needle thread of a line of stitching that comprises a needle thread and a looper thread, the said needle thread having loops extending from one side of the'bag through the needle holes, the looper thread being on the other side of the bag and securing said loops from pulling out through the needle holes, said loops of the needle thread plugging ,the needle holes, said looper thread also being a composite thread of the same character as the needle thread.

References Cited in the file of this patent UNITED STATES PATENTS 2,278,156 Sterling Mar. 31, 1942 2,477,652 Robbins Aug. 2, 1949 2,526,523 Weiss Oct. 7, 1950 

